Steam Error: Disk could not be authenticated while installing Half-Life 2

We have received a few reports of players being unable to play because they receive a "Disk could not be authenticated" error. The problem is usually fixed by having them move the disk they are trying to play from to the first lettered drive available. I.E. if you are trying to run the disk from your dvd burner g:\ move it to your dvd player f:\. If this does not fix the issue please check for any firmware upgrades for your drives as well.

Also, the software Sonic DLA, Any DVD, and Alcohol 120%, have been conflicting with the retail CD's, you may need to uninstall this software before the disks will be recognized properly.